Chairs often include backrests, or a chair back. A backrest may be stationary or may be reclinable. Some office chairs or other chairs may also include a seat that is rotatable. When the chair seat rotates, the back may also rotate with the seat due to the back's connection to the seat. Examples of chairs that include chair backs can be appreciated from U.S. Pat. Nos. 8,480,171, 8,469,454, 8,419,133, 8,348,342, 8,282,172, 8,002,351, 7,547,067, 6,932,430, 6,869,142, 6,817,667, 6,733,080, 6,598,937, 6,367,876, 6,086,153, 6,048,029, 5,755,490, 5,725,277, 4,380,352, 4,235,408, 4,219,233, 3,910,633, 3,863,982, 3,055,628, 3,042,448, and 2,650,648.